如何使用 ggplot 在同一图中绘制两个平滑样条线？

Question

例如，我有几个这样的图：

ggplot(mpg, aes(displ, hwy)) +
geom_point() +
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T)

是否可以将 2 个此类绘制到同一个图中？

Answer 1

如果您只想添加另一个功能，请添加另一个层：+ geom_smooth()

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T) +
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 4), se = T)

如果您想从不同的数据框中添加数据，请df在其中添加信息geom_smooth：

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T) + 
geom_smooth(data = mpg, aes(x = displ, y = cyl), method = "lm", formula = y ~ splines::bs(x, 4), se = T)

最后，自定义颜色和图例： color参数需要位于内部aes才能出现在图例中

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(aes(color = "B"),method = "lm", formula = y ~ splines::bs(x, 3), se = T) + 
geom_smooth(data = mpg, aes(x = displ, y = cyl, color = "A"), method = "lm", formula = y ~ splines::bs(x, 4), se = T) + 
scale_color_manual("Legend Title", values = c("A" = "red", "B" = "blue"))